Restaurants, especially fast food restaurants, produce high volumes of waste grease (from fatty foods) that is typically, and unavoidably, discharged through roof-mounted exhaust systems. These roof-mounted systems are conventionally built with an exhaust fan unit mounted atop a base, or pedestal, that projects upwardly from the roof. The grease discharged upward from these systems, however, often accumulates on the roof. Conventional roofing products will generally become soft and will deteriorate following prolonged exposure to these organic fats and oils, leading to roof failure. Moreover, grease and oil can create safety problems for maintenance workers and the increased potential for fire. Furthermore, water runoff from the rooftop may be contaminated from the grease and oil, creating pollution problems in the vicinity of the restaurant.
Numerous attempts to contain the grease discharged from restaurant exhaust systems have resulted in less than effective or efficient methods and systems. One such attempt has been the installation of polycarbonate roof exhaust fan gutter systems (see FIG. 1, gutter 140 mounted around the exhaust fan 150 and exhaust fan pedestal 110 interface) to collect grease discharged from the exhaust fans; however, grease is not prevented from seeping between the hard, substantially inflexible contact surfaces, contaminating the surface of the roof. Additionally, these gutters must be periodically emptied and cleaned, or replaced, requiring substantial labor and maintenance costs. If not cleaned on a regular basis, the gutters fill up and run over, defeating their intended function.
Another known construction comprises a frame structure which is directly mounted to the roof (see FIG. 2, frame structure 232 and sorbent layered material 234 mounted about exhaust fan 250 pedestal 210 adjacent the roof 205) and surrounds the pedestal upon which the exhaust fan is mounted. The frame structure 232 holds one or more layers of sorbent material 234 in place. Unfortunately, grease still seeps down between the exhaust fan pedestal 210 and the frame structure 232, soiling the roof. Additionally, where the roof has any slope whatsoever, the frame construction becomes problematic to install and is only marginally effective at containing discharged grease. Moreover, constructions of this type require very labor intensive installations and frequent replacement of soiled sorbent materials. In many municipalities, building codes prohibit such installation techniques.
Yet other attempts to contain grease have involved the construction of filters that are attached to grease discharge spouts; however, such constructions fail to capture grease that tends to migrate through other openings, seams, or the juncture of the exhaust fan and exhaust fan pedestal.